I would like to find (symbolically) inverse of certain 3x3 matrices
which are block partitioned. For example for 2x2 case the following
solution is available
http://www.cs.nthu.edu.tw/~jang/book/addenda/matinv/matinv/
However, I would like to find inverse of 3x3, and 4x4 block matrix
A B C
D F G
H I J
where A, B, C ... are matrices themselves. Thanks in advance.